FBI Director Robert Mueller told the House Judiciary Committee that “all necessary steps” will be taken to hold Snowden responsible for his admitted leaking.

“These disclosures have caused significant harm to our nation and to our safety,” Mueller told lawmakers. “As to the individual who has admitted to making these disclosures, he is the subject of an ongoing criminal investigation.”

The lawman added: “We are taking all necessary steps to hold the person responsible for these disclosures.”

The Los Angeles Times reported today that Snowden used a thumb drive to steal documents from the NSA’s facility in Hawaii, where he worked.

Thumb drives are generally banned from NSA buildings because of they can help users grab huge document loads with relative ease.

But Snowden, as a system administrator, might have had special permission to have thumb drive on the job, an NSA source told the Los Angeles newspaper.

“Of course, there are always exceptions (to the thumb drive ban),” a former NSA official said. “There are people who need to use thumb drive and they have special permission. But when you use one, people always look at you funny.”

The NSA reportedly has a good handle on what Snowden stole.

Investigators “know how many documents he downloaded and what server he took them from,” said an agency official.

Snowden has been hiding out in Hong Kong, since spilling his guts about the NSA’s telephone and Internet espionage.

He’s ingratiated himself to Chinese hosts, singing like a canary about US hacking efforts aimed at Hong Kong and mainland institutions.

Snowden told the South Morning China Post that the NSA has been regularly targeting Hong Kong and the People’s Republic of China with hack attacks since at least 2009.

He showed the English-language daily documents that allegedly chronicled his hacking claims.

“Last week the American government happily operated in the shadows with no respect for the consent of the governed, but no longer,” Snowden said in editions of today’s paper. “Every level of society is demanding accountability and oversight.”

The Chinese University of Hong Kong, public-office holders, businesses and students were among NSA targets in the semi-autonomous city, according to the American turncoat.

None of the documents shown to the SCMP showed information of military systems.

“We hack network backbones – like huge Internet routers, basically – that give us access to the communications of hundreds of thousands of computers without having to hack every single one,” he said.

“The hypocrisy of the US government when it claims that it does not target civilian infrastructure, unlike its adversaries”.

Snowden added: “Not only does it do so, but it is so afraid of this being known that it is willing to use any means, such as diplomatic intimidation, to prevent this information from becoming public.”

The former NSA contractor said US authorities are pressuring China and Hong Kong to kick him out.

“Unfortunately, the US government is now bullying the Hong Kong government to prevent me from continuing my work,” Snowden said.

The former British colony is under the ultimate rule of the People’s Republic of China. But Hong Kong is run as a special administrative region, maintaining Western-style courts and freedom of speech, left behind by the British.

“I do not currently feel safe due to the pressure the US government is applying to Hong Kong, but I feel that Hong Kong itself has a strong civil tradition that whistleblowers should not fear,” Snowden said.

He’s not reached out to his family or dancer girlfriend since going public with NSA secrets, according to the high-school dropout and computer whiz.

“I have not spoken to any of my family,” Snowden said. “I am worried about the pressure they are feeling from the FBI.”

On her blog, Lindsay Mills has said she was completely taken off guard by Snowden taking off for Hong Kong and blabbing about American secrets.

Jonathan Mills backed up his daughter’s story and said “she’s all right,” “staying with friends” and “thinking about trying to start putting the pieces back together again.”

Long before he became known worldwide as the National Security Agency contractor who exposed top-secret US government surveillance programs, Snowden worked for a Japanese anime company run by friends and went by the nicknames “The True HOOHA” and “Phish.”

In 2002, he was 18 years old, a high school dropout and his parents had just divorced. On the tiny anime company’s Web site, he wrote of his skills with video games and popularity with women.

In an online forum eight years later, he apparently again used the screen name “The True HOOHA” in a discussion of surveillance by a private computer company for the government.

“It really concerns me how little this sort of corporate behavior bothers those outside of technology circles,” the post from 2010 reads. “Society really seems to have developed an unquestioning obedience towards spooky types.”

Snowden, a former CIA employee who turns 30 later this month, does not appear to be otherwise active on social media sites like Facebook or Twitter — at least not under his own name.

But the Web site of Ryuhana Press, a defunct start-up that sold anime art, offers a glimpse of Snowden as a youth. As its web editor, Snowden’s profile page is a mix of truth, sarcasm and silly jokes.

For example, he listed his correct birthday – June 21, 1983 – and noted that it fell on the summer solstice, the longest day of the year. But he also claimed to be 37 years old and to have fathered two preteen children.

“I really am a nice guy,” Snowden wrote on his profile page. “You see, I act arrogant and cruel because I was not hugged enough as a child, and because the public education system turned it’s (sic) wretched, spiked back on me.”

Reuters viewed the Web site on Tuesday and contacted former company employees for comment. On Wednesday, the Web site had been taken down.

Snowden wrote that he favored purple sunglasses and praised the Baltimore Orioles baseball team.

“I like my girlish figure that attracts girls,” he wrote, “and I like my lamer friends. That’s the best biography you’ll get out of me, coppers!”

Photographs uploaded by friends for Snowden’s 19th birthday show a young man pulling down his pants for his colleagues, putting a clothespin on his chest, and dancing. A blog entry from a company employee teased: “Who is he? What does he do? Does he really love himself as much as his shameless marketing would have you believe?”

Within years, he took a job as a security guard at the NSA and by age 23, Snowden was working undercover overseas for the CIA on classified computer systems. He went to work for a private contractor in 2005, congressional officials said Wednesday.

In postings a year later on the Ars Technica Internet message board, he apparently again used “The True HOOHA” screen name. The later Ars Technica postings were first reported by the New York blogger Anthony De Rosa.

He wrote that he joined the CIA for the opportunity to travel abroad. He also wrote about his concerns regarding government wiretapping. In 2006, “TheTrueHOOHA” wrote: “NSA’s new surveillance program. That’s the sound of freedom, citizen!”

In the earlier postings as an 18-year-old, Snowden wrote on his profile that he liked online role-playing games, or RPG. “I always wanted to write RPG campaigns with my spare time, but I’ll get about three missions in and scrap the world for my next, better, powergamin’ build.”

He joked that he “got bullied” into being an editor on the Web site by a gaggle of artists and “beautiful nubile young girls.”

Snowden said he liked playing the popular fighting video game Tekken. He was so skilled that he attracted a gathering of fans at the 2002 Anime USA convention, a co-worker wrote on another part of the site. “He tends to spontaneously be a ray of sunshine and inspiration. He’s a great listener, and he’s eager to help people improve themselves.”

The co-worker did not reply to inquiries from Reuters on Wednesday. Ryuhana closed in 2004 as the primary proprietors went off to college and opened a new business in California, according to the Web site. Other contributors to the site could not be reached for comment.

Additional reporting by Andy Soltis in New York and S.A. Miller in Laurel, Md. With Reuters